1. Technical Field
This invention relates to electrical switching assemblies, and more particularly to a power control switching circuit for high current switching. The power control switching circuit is particularly well adapted for use with power window control circuits in motor vehicles which utilize power driven window assemblies.
2. Discussion
Power windows are now commonly offered in many motor vehicles such as automobiles and trucks. Such power windows usually incorporate at least one DC motor for driving the window up and down in response to an operator actuatable switch. The current required to drive such motors is usually fairly high, and most often well above that which would ordinarily be capable of being transmitted by printed circuit boards. As is well known, conventional printed circuit boards have traditionally been limited to low current applications where currents are kept generally below about 0.5 amps. The current typically required for driving motors associated with power window control circuits is generally ranges from about 20 to 80 amps.
Heretofore, the standard approach to automotive switch control design has involved insert molding technology. This involves using a plurality of independent brass or copper lead frames (i.e., conductors) to carry high electrical current between a vehicle wiring harness and the switch contacts of an operator accessible switch control. These lead frames are typically imbedded in a plastic body or substrate. This process generally requires specialized injection mold tooling and techniques which can accommodate variously shaped and sized lead frames. Frequently, "two shot" molding is required in which the plastic material above and below the portions of the lead frame is injected into the mold in sequential steps. Such apparatus and procedures are relatively expensive and time consuming and add to the complexity and cost of power window control circuits in view of the increased tooling expense required to produce such assemblies. Also, the plastic body portion described above is typically restricted to accommodating only the lead frames and associated switch contacts. Thus, a separate printed circuit board is typically needed for the electronic components of the control circuit. This also significantly increases the overall cost of the control circuit.
Accordingly, it is the principal object of the present invention to provide a power switching control module which can be used with a conventional printed circuit board to enable high current switching for use in power window control circuits and automotive vehicles.
It is still another object of the present invention to provide a power switching control module in which high current traces are employed on the surface of a printed circuit board in lieu of imbedding a portion of a lead frame within an independent plastic body piece, to thereby eliminate the need for injection molding tooling and techniques.